Hydromethanation is a process for producing methane from carbon-rich feedstocks such as coal, petroleum coke, or biomass. In this process, carbon is converted through a combination of catalytic reactions in the presence of water into methane. FIG. 1 provides a schematic of an example system in which the hydromethanation process can be carried out.
As shown in FIG. 1, the hydromethanation process is typically carried out in a fluidized bed reactor 13. A mixing stage 11 is employed to mix the carbon-rich feedstocks with a catalyst. Typically, the feedstocks are ground into fine particles to which the catalyst adheres. This mixture is then loaded into fluidized bed reactor 13 where pressurized steam fluidizes the mixture to maintain constant contact between the carbon and the catalyst. This constant contact promotes a series of reactions that convert the carbon and water into methane and carbon dioxide.
Solid byproducts of the process, including the catalyst, can be recovered through a catalyst recovery stage 12 which feeds the recovered catalyst back to mixing stage 11 for reuse. The methane and carbon dioxide escape upwardly where they are piped through a cyclone stage 14 for removing particulates, a cooling stage 15, and a gas separation stage 16. Gas separation stage 16 is employed to remove the carbon dioxide and any other gas byproducts (e.g., ammonia, sulfur, or other impurities found in the feedstocks) from the methane.